Liner wear detection

ABSTRACT

Methods and apparatus for detecting wear in a liner. In one embodiment of the present invention, an electrically conductive wire is placed on or near the outside surface of the liner and the electrical resistance in the electrically conductive wire is measured to determine whether the wire has worn through. In another embodiment of the present invention, the temperature measured by a temperature measuring device, such as a thermocouple, is monitored over time to estimate wear in the liner.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional of U.S. patent application Ser. No.10/670,586 filed Sep. 25, 2003, the specification of which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention generally relates to apparatus for changing thedirection of a fluid flow, especially of highly abrasive fluid flows inlined piping systems. In preferred embodiments, the present inventionrelates to changing the direction of flow of such fluids in a smallspace with a smaller pressure loss or pressure drop than is found whenusing conventional technology to change the direction of a fluid flow.

BACKGROUND AND SUMMARY OF THE INVENTION

In any enclosed system containing a flowing fluid, such as a pipingsystem, there is frequently a need to make directional changes in thefluid flow. Typically, standard piping elbows, also referred to asbends, are used. However, circumstances frequently exist that imposeconstraints and preclude the use of standard piping elbows. Thesecircumstances include the conveying of high temperature fluids,corrosive fluid streams, or abrasive fluid streams such as those thatare particulate-laden fluid streams. When these conditions exist, atypical solution to changing the fluid flow direction often involvesusing larger size (that is, greater diameter) piping elements lined withan appropriate refractory, corrosion-resistant, or abrasion-resistantlining.

An increase in the piping diameter requires an accompanying increase inthe turning radius of any needed bends. The increase in turning radiusin turn increases the space requirements for installing an elbow or bendneeded to make a change in the fluid flow direction. Utilizing an elbowor bend with too small of a turning radius typically causes anundesirable pressure loss.

As related in a commonly-assigned application filed concurrently withthe present application, the inventors have addressed these deficienciesby providing a piping elbow capable of facilitating a fluid flowdirection change in a smaller space than conventional piping elbows,without causing the larger pressure losses found when using conventionalelbows in the equivalent space. These piping elbows comprise asubstantially-cylindrical body having a first end, a second end, and asubstantially-constant inside diameter; a tangential inlet attached tothe body near the first end of the body and having an inside diametersmaller than the inside diameter of the body; and a tangential outletattached to the body near the second end of the body and having aninside diameter smaller than the inside diameter of the body. Typically,fluid flows linearly through the tangential inlet and enters the body.Inside the body, linear motion of the fluid is converted into arotational or spiral motion. The fluid in the body continues its spiralmotion as it also moves axially through the body toward the tangentialoutlet. The fluid exits the body through the tangential outlet. Uponexiting through the tangential outlet, rotational or spiral motion ofthe fluid in the body is converted back into linear motion.

In a preferred embodiment, the piping elbows comprise twosubstantially-identical components attached to each other. In anotherpreferred embodiment, the two substantially-identical components areremovably attached to each other so that the tangential inlet/outlet onthe first component can be oriented at any desired angle with respect tothe tangential inlet/outlet on the second component.

Together with the development of the described piping elbows, and asrelated in a further commonly-assigned application filed concurrent withthe present application, the inventors have additionally conceived aliner for use with the piping elbows. In one embodiment, the linercomprises a body liner, a tangential inlet liner, and a tangentialoutlet liner. In a preferred embodiment, the tangential inlet liner andthe tangential outlet liner are each removably inserted into a cavity inthe body liner. In another embodiment, the body section liner comprisestwo substantially-identical body section liners.

The present application, in a preferred embodiment, concerns methods andapparatus for detecting wear in such liners, though it will beappreciated that the inventive methods and apparatus are more broadlyapplicable to the whole of lined vessels generally (and “vessels” hereshould be taken as referring to any structure in or through which afluid, especially an abrasive fluid, moves). In one embodiment, anelectrically conductive wire is placed on or near the outside surface ofthe liner (relative to the fluid flow) and the electrical resistance inthe electrically conductive wire is measured to determine whether thewire has worn through. In another embodiment, the temperature measuredby a temperature measuring device, such as a thermocouple, is monitoredover time to estimate wear in the liner.

DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example in the followingdrawings in which like references indicate similar elements. Thefollowing drawings disclose various embodiments of the present inventionfor purposes of illustration only and are not intended to limit thescope of the invention.

FIG. 1 shows a piping elbow having a tangential inlet and tangentialoutlet that are axially oriented in substantially opposite directions.

FIG. 2 shows a top-down view of the piping elbow of FIG. 1.

FIG. 3 shows a top-down view of a piping elbow with a tangential inletand tangential outlet that are axially oriented at about 90 degrees toeach other.

FIG. 4 shows a top-down view of a piping elbow with a tangential inletand tangential outlet that are axially oriented in substantially thesame direction.

FIG. 5 shows a piping elbow of the type shown in FIG. 1 but which iscomprised of two substantially identical component sections, providing atangential inlet and tangential outlet that are axially oriented insubstantially-opposite directions.

FIG. 6 shows the piping elbow of FIG. 5, wherein the two componentsections have been attached so that the tangential inlet and tangentialoutlet are axially oriented at about 90 degrees to each other.

FIG. 7 shows the piping elbow of FIG. 5, wherein the two componentsections have been attached to provide a tangential inlet and tangentialoutlet that are axially oriented in substantially the same direction.

FIG. 8 shows an exploded view of one of two substantially-identicalpiping constructs reflected in FIGS. 5 through 7.

FIG. 9 shows an exploded view of two piping constructs of FIG. 8removably attached to each other.

FIG. 10 shows another view of the body section liner and tangentialinlet liner shown in FIGS. 8 and 9.

FIG. 11 shows the tangential inlet liner of FIGS. 8, 9, and 10 insertedinto the cavity of the body section liner of FIGS. 8, 9, and 10.

FIG. 12 shows a schematic of the body section liner of FIG. 10.

FIG. 13 shows a schematic of the tangential inlet liner of FIG. 11.

FIG. 14 shows a cylindrically-shaped section of a liner having anelectrically conductive wire placed near the outside surface of theliner in a zigzag pattern in accordance with the present invention.

FIG. 15 shows a cross-sectional view of the body section liner shown inFIG. 14

FIG. 16 shows a cylindrically-shaped section of a liner having anelectrically conductive wire placed near the outside surface of theliner in a spiral pattern in accordance with the present invention.

FIG. 17 shows a cross-sectional view of the liner section shown in FIG.16.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In the following detailed description of preferred embodiments of thepresent invention, reference is made to the accompanying Drawings, whichform a part hereof, and in which are shown by way of illustrationspecific embodiments and contexts in which the liner wear detectionmethods and apparatus of the present invention may be practiced. Itshould be understood that other embodiments may be utilized and changesmay be made without departing from the scope of the present invention.

The piping elbows to which the present inventive methods and apparatusare applied in preferred embodiments comprise asubstantially-cylindrical body having a first end and a second end andhaving a substantially-constant diameter; a tangential inlet attached tothe body section near the first end of the body section and having adiameter smaller than the diameter of the body section; and a tangentialoutlet attached to the body section near the second end of the bodysection and having a diameter smaller than the diameter of the bodysection. Unless specified otherwise herein, the word “diameter” willrefer to the inside diameter of an article.

For purposes of the present specification the first end of the bodysection may from time to time also be referred to as the “top” of thebody, and thus the “top” of the piping elbow, while the second end maybe referred to as the “bottom” of the body and the “bottom” of thepiping elbow. While the words “top” and “bottom” may be used as a matterof convenience in the course of the present description to indicatespecific ends of the body and piping elbow, the use of the words “top”and “bottom” rather than “first end” or “second end” should not be takento indicate or imply that the piping elbows in which the liner detectionmethods and apparatus find application necessarily arevertically-oriented or have a “top” or “bottom” end—the ends may be atthe same elevation.

In a piping elbow of the type shown in the drawings, fluid flowslinearly through the tangential inlet and enters the body. Inside thebody, essentially linear motion of the fluid is converted into arotational or spiral motion. The fluid in the body continues its spiralmotion as it also moves axially through the body section, toward thetangential outlet. The fluid exits the body through the tangentialoutlet. Upon existing through the tangential outlet, rotational orspiral motion of the fluid in the body is converted back into linearmotion.

FIG. 1 shows an example of such a piping elbow 100. The piping elbow 100comprises a tangential inlet 102, a body 104, and a tangential outlet106. In a typical operation of the piping elbow 100, fluid flowsessentially linearly through the tangential inlet 102, as indicated bythe arrow 108, and enters the body 104. Upon entering the body 104,linear motion of the fluid flow is converted to a spiral motion as thefluid moves axially from the tangential inlet 102 toward the tangentialoutlet 106. Upon reaching the tangential outlet 106, spiral motion istranslated back to linear motion as the fluid exits the body 104 asindicated by the arrow 110.

In order to facilitate the spiral motion of the fluid in the body,inlets and outlets according to the present invention are both smallerin diameter than the body. By tangential it is meant that the axis ofthe inlet (or outlet) does not pass through the axis of the body. Thetangential inlet and tangential outlet can also be thought of as beingoff-center in relation to the body. The tangential nature of the inletand outlet are more clearly illustrated in FIG. 2. FIG. 2 shows atop-down view of a piping elbow 200 similar to the piping elbow 100illustrated in FIG. 1. The piping elbow 200 comprises a tangential inlet202, a body 204, and a tangential outlet 206. As shown in FIG. 2, theaxis 208 of the tangential inlet 202 does not intersect with the axis210 of the body 204. If a tangential inlet were centered with respect toa body, then the axis of the tangential inlet would intersect the axisof the body. Similarly, the axis 212 of the tangential outlet 206 doesnot intersect with the axis 210 of the body 204.

Fluid enters the body 204 through the tangential inlet 202 as indicatedby the arrows 214. Inside the body 204, fluid travels toward thetangential outlet in a spiral motion as indicated by the arrows 216.Upon reaching the tangential outlet 206, fluid exits the body asindicated by the arrows 218.

The tangential inlet and tangential outlet are both smaller in diameterthan the body. For many applications, the diameter of the tangentialinlet will be about the same size as the diameter of the tangentialoutlet. Preferably, the diameter of the body is at least about 1.5 timesas large as the diameter of the tangential inlet and the diameter of thetangential outlet. More preferably, the diameter of the body is at leastabout 2 times as large as the diameter of the tangential inlet and thediameter of the tangential outlet. Preferably, the diameter of the bodysection is no more than about 3 times as large as the diameter of thetangential inlet and the diameter of the tangential outlet.

The tangential inlet and tangential outlet may be axially-oriented inany direction relative to each other. For example, in FIG. 2 thedirection of the fluid flow in the tangential inlet 202 is in theopposite direction of the fluid flow in the tangential outlet 206. Thatis, the direction of the fluid flow in the tangential inlet 202 is about180 degrees in relation to the fluid flow in the tangential outlet 206.Thus, the tangential inlet 202 is axially-oriented in the oppositedirection of the tangential outlet 206. A piping elbow having atangential inlet and a tangential outlet axially-oriented insubstantially the opposite direction can be advantageously utilized whenthe elbow is part of a piping system serving as a return, such as when aproduct of a production system is returned or recycled back into theproduction system. The tangential inlet can be at the same elevation ora different elevation than the tangential outlet depending on the needsin any application.

To facilitate the exit of the fluid flow through the tangential outlet,the tangential outlet should be positioned on the opposite side of thebody section's axis than the tangential inlet when the inlet and outletare axially-oriented in the opposite direction. For example, in thetop-down view of piping elbow 200 shown in FIG. 2 the axis 208 of thetangential inlet 202 appears to the left of the body's axis 210 and theaxis 212 of the tangential outlet 206 appears to the right of the body'saxis 210. The positioning of the tangential inlet 202 to the left of thebody's axis 210 causes the fluid flow in the piping elbow 200 to spiralin a clockwise motion as indicated by the arrows 216. As the fluid flowcontinues to spiral it moves axially through the body 204 from thetangential inlet 202 to the tangential outlet 206. As the fluid flowreaches the tangential outlet 206, the fluid flow is moving in thedirection needed to exit through the tangential outlet 206 as indicatedby the arrows 220 and 218. The tangential inlet 202 and the tangentialoutlet 206 can in this circumstance be described as “rotationallyaligned.” If on the other hand, the tangential outlet 206 had beenpositioned directly underneath the tangential inlet 202 such that bothaxis 208 and 212 were positioned to the left of the body's axis 210,then as the fluid flow reached the tangential outlet 206 it would not bemoving in the same direction as needed to exit the tangential outlet206.

FIG. 3 and FIG. 4 illustrate other examples of piping elbows wherein thetangential inlet and tangential outlet are rotationally aligned. In FIG.3, the piping elbow 300 comprises a tangential inlet 302, a body 304,and a tangential outlet 306, wherein the tangential inlet 302 and thetangential outlet 306 are rotationally aligned and are axially orientedat about 90 degrees to each other. In FIG. 4, the piping elbow 400comprises a tangential inlet 402, a body 404, and a tangential outlet406, wherein the tangential inlet 402 and the tangential outlet 406 arerotationally aligned and are axially oriented in substantially the samedirection.

Piping elbows as illustrated in FIGS. 1-4 can be manufactured as onesolid piece (as shown in FIG. 1) or, more preferably, can bemanufactured in parts that can be assembled to form the piping elbow. InFIG. 5, the piping elbow 500 comprises a tangential inlet 502, a bodyassembled from two body sections 504 and 505, and a tangential outlet506, wherein the tangential inlet 502 and the tangential outlet 506 arerotationally aligned and are axially oriented in substantially theopposite direction. Preferably, tangential inlet 502 and first bodysection 504 comprise a single continuous piece and tangential outlet 506and second body section 505 comprise a second single continuous piece.The body of the piping elbow 500 is assembled by attaching the flange518 of the first body section 504 to the flange 520 of the second bodysection 505 in conventional manner. The top 514 of the first bodysection 504 is attached to the first body section 504 and the bottom 516of the second body section 505 is attached to the second body section505. The first body section 504 and the second body section 505 can beseparated after use so that the interior of the body can be inspectedand cleaned, if necessary. Similarly, the top 514 and bottom 516 areremovable so that the interior of the body can be inspected and cleanedas needed. Additionally, the piping elbow 500 can be removed from therest of the piping system to facilitate inspection, cleaning, repair,replacement, etc. by separating flange 522 from flange 524 andseparating flange 526 from flange 528.

Alternate configurations are also possible. For example, the top 514and/or bottom 516 of body sections 504 and 505 respectively may bepermanently attached instead of removably attached as described above.The top 514 and/or bottom 516 may be permanently attached in any waysuitable for the particular application. For example, the top 514 and/orbottom 516 can be manufactured as one continuous component along withbody-section 504 and/or body-section 505.

Most preferably, for simplicity and ease of manufacture thebody-sections 504 and 505 are substantially identical to one another,and removably attached via flanges 518 and 520 in a reverse mirror-imagerelationship. Thus, in FIG. 5, the piping elbow 500 can be separatedinto two substantially-identical components by separating flange 518from flange 520. The first substantially-identical component comprisesbody section 504, tangential inlet 502, and top 514. The secondsubstantially-identical component comprises body section 505, tangentialoutlet 506, and bottom 516.

FIGS. 5-7 illustrate another advantage of piping elbows that comprisetwo substantially-identical components. That is, the bottom componentcan be oriented at a selected degree relative to the top component toprovide a desired redirection of the fluid flow in moving from thetangential inlet through the body and out through the tangential outlet.For example, FIG. 6 shows the piping elbow 500 of FIG. 5 with the bottomcomponent at an angle of approximately 90 degrees relative to the topcomponent. That is, piping elbow 600 of FIG. 6 comprises the exact samecomponents of piping elbow 500 except that the bottom component isrotated approximately 90 degrees. Similarly, FIG. 7 shows piping elbow700 comprising the exact same components of piping elbow 500 except thatthe bottom component is rotated approximately 180 degrees.

Piping elbows as illustrated and described above may include coolingjackets. Cooling jackets are known in the art for cooling materialsinside vessels or piping systems. For example, piping elbow 500comprises a cooling jacket. As shown best in FIG. 5, both the first bodysection 504 and second body section 505 of the piping elbow 500 comprisea cooling jacket that includes a water inlet and water outlet, in thecase of body section 504 being inlet 508 and outlet 510. The water inletfor body section 505, which is symmetric to water inlet 508 and in thesame relationship to outlet 512 as inlet 508 is to outlet 510, is notshown.

Piping elbows to which the present inventive methods and apparatus applyadditionally comprise a liner made of material suitable to theenvironment in which the piping elbow will be used, and especially beingsuitable for use with abrasive fluids. For example, ceramic liners canbe advantageously utilized with piping elbows such as piping elbow 500of FIG. 5 in a TiO₂ production process. After the burner section oroxidation section in a TiO₂ production process, the TiO₂ is carried bythe process gases through a cooling section. The cooling section is botha highly abrasive environment and a high temperature environment. It isnot unusual for the temperature of the fluid stream comprising TiO₂ andprocess gases to vary between 400° F. (204.44° C.) and 1400° F. (760°C.). Piping elbows with ceramic liners can be advantageously utilized inthis cooling section of a TiO₂ production process.

In one embodiment, the liners used will comprise a body liner, atangential inlet liner, and a tangential outlet liner. In a preferredembodiment, the tangential inlet liner and the tangential outlet linerhave substantially the same shape. That is, the tangential inlet linerand the tangential outlet liner are substantially identical. The bodyliner may comprise a single continuous component or may comprisemultiple section liners. In a preferred embodiment, the body linercomprises two substantially-identical body section liners. Each of thetwo substantially-identical body section liners has a cylindrical shapethat is open at one end and closed at the other end. The closed end canbe closed by removably attaching an end to the body section liner or bymanufacturing the body section liner as one continuous piece having aclosed end. In one embodiment, at least one body section liner has aremovably attached end functioning as either a top or bottom of theliner, which can be removed to inspect or clean the inside of the bodysection liner.

FIG. 8 shows an exploded view of a component 800, which is one of twosubstantially-identical components that can be removably attached toeach other to form a piping elbow as described above. The component 800is similar to the top component shown in FIG. 5 and comprises a bodysection 804, a tangential inlet 802, and a top 814. It should be notedthat if component 800 were used as a bottom component instead of a topcomponent, then the tangential inlet 802 would function as a tangentialoutlet. Component 800 further comprises a tangential inlet liner 806, abody section liner 808, and a top liner 810. During the process ofputting component 800 together, the body section liner 808 is insertedinto the body section 804 and then the tangential inlet liner 806 isinserted into the tangential inlet 802 such that the tangential inletliner 806 fits into the cavity 812 in the body section liner 808. Thetangential inlet liner 806 and the cavity 812 are shaped such that theedges of the tangential inlet liner 806 line up with the edges of thecavity 812. Thus, the shape of the cavity 812 in the body section liner808 is substantially identical to the shape of the inserted end of thetangential inlet liner 806. The construction of component 800 isfinished by placing the top liner 810 onto the body section liner 808,placing insulation 816 onto the top liner 810, placing a gasket 818 ontop of the body section 804, applying a gasket sealer 820 on top of thegasket 818, and then attaching the top 814 to the body section 804. InFIG. 8, the top 814 is removably attached to the body section 804 bybolting the top 814 to the body section 804. FIG. 9 shows an explodedview of two components 800 removably attached to each other to form apiping elbow.

FIGS. 10-11 illustrate how tangential inlet liners and tangential outletliners fit into a cavity of either a body liner or a body section linerto form a liner joint. FIG. 10 shows the tangential inlet liner 806, thebody section liner 808, and the cavity 812 of FIGS. 8 and 9. As shown inFIG. 10, the shape of the inserted end of the tangential inlet 806 issubstantially identical to the shape of the cavity 812 in the bodysection liner 808. FIG. 11 shows the tangential inlet liner 806 insertedinto the cavity 812 of the body section liner 808 forming a linercomponent 1100 suitable for use in a first component of a piping elbow.The point at which an inlet or outlet is inserted into the cavity of abody liner or body section liner may be referred to herein as a linerjoint.

The cavity in a body liner or body section liner can be created byremoving a plug from a cylindrical piece of lining material. Ceramicpieces of lining material may be purchased from Ceramic ProtectionCorporation, for example. To remove the plug, the intersection of theinlet (or outlet) axis with the body is located. Projecting along thisaxis, a plug is removed that is approximately equal in diameter to theoutside diameter of the inlet (or outlet) to be inserted plus anyrequired tolerances. The plug is made to a depth such that the edge ofthe inlet (or outlet) liner is aligned with the internal surface of thebody liner. FIG. 12 shows a schematic that illustrates a body sectionliner 1200 having an outside diameter 1202 of 13½ inches (34.29 cm), aninside diameter 1204 of 12 inches (30.48 cm), and a height 1206 of 17½inches (44.45 cm). The radius 1208 of the cavity 1210 is 4 13/16 inches(12.22 cm) with the distance 1212 from the end 1214 of the body sectionliner 1200 to the axis 1216 of the cavity 1210 being 5¾ inches (14.61cm). The distance 1218 from the axis 1216 of the cavity 1210 to theoutside edge of the body section liner 1200 is 4¾ inches (12.07 cm).

Tangential inlet liners and tangential outlet liners also can be createdby removing a plug from a cylindrical piece of lining material. Theinlet and outlet liners can be created by removing a cylindrical plughaving a diameter approximately the same diameter as the inside diameterof the body liner into which the inlet or outlet liner is to beinserted. FIG. 13 shows a schematic that illustrates a tangential inlet(or outlet) liner 1300 having an outside diameter 1302 of 9½ inches(24.13 cm), an inside diameter 1304 of 8 inches (20.32 cm), and a height(or length) 1306 of 12 inches (30.48 cm). As illustrated in FIG. 13,tangential inlet liner 1300 has a cylindrical shape having a height 1306of 12 inches (30.48 cm) and an outside diameter 1302 of 9½ inches (24.13cm). The cylindrical shape of tangential inlet liner 1300 has acylindrical plug removed with a radius 1308 of 6 inches (15.24 cm)removed from the end of the tangential inlet liner 1300. The axis 1310of the cylindrical plug is a distance 1312 of 2 inches (5.08 cm) fromthe axis 1314 of the tangential inlet liner 1300 at its closest point.It should be noted that the radius 1308 of the removed cylindrical plug(that is, 6 inches (15.24 cm)) matches the inside diameter 1204 (thatis, 12 inches (30.48 cm)) of the body liner 1200.

Liners of the type described herein have several advantages over linersused in the prior art. When refractory brick or tile liner systems areused in process lines or equipment as is known in the art, the linermaterials are typically bonded in place by gluing or grouting. Onceinstalled, demolition of the liner system is necessary whenever theliner system must be removed. Bricking and demolition of the linersystem are time-consuming and require fresh material to be installedevery time. Liners as we have described, on the other hand, allow theliner system in certain applications to be installed and removedrepeatedly without damaging the liner materials.

Straight piping lines of the prior art offer the opportunity to insertpre-cast liner sections. However, these liner sections are still usuallybonded in place to keep the liner from moving out of position or fallingout of the body. Lining a junction such as a tee or a vessel inlet witha vessel body typically requires some type of locating, alignment, orlocking method or device. In many cases, this is done by grouting orbonding the parts in place. Once that is done, removal is difficult orimpossible without breakage of the liner system. Liners as describedherein provide a joint design that aligns and holds the parts of theliner in place with respect to one another, requiring little or nogrouting or bonding to maintain the integrity of the joint. That is,once a body liner is inserted into the body of a piping elbow in keepingwith FIGS. 8-13, for example, the insertion of a tangential inlet linerand a tangential outlet liner into the cavity of the body liner holdsthe body liner in place with little or no bonding. Similarly, if thetangential inlet liner and tangential outlet liner are removed, the bodyliner can be removed for inspection or replacement. In this manner, thetangential inlet liner and the tangential outlet liner are removablyinserted into the cavity of the body liner and the body liner isremovably inserted into the body of a piping elbow.

Both liners as described and shown herein and liners previously known tothe art can be advantageously utilized with various methods according tothe present invention, for detecting wear in the liner. Such methods canbe extremely important for applications in which the liner contains aflow or movement of abrasive fluids, whether in a vessel, a section ofpipe, or a piping elbow of the type described above. One such methodutilizes an electrically conductive wire placed on the outside surfaceof the liner relative to the flowing or moving fluid. The electricalresistance of the wire is periodically measured to determine whether thewire has worn through. If the wire is intact it will have a relativelylow electrical resistance. However, if the liner is worn through, theabrasive environment that caused the liner to wear through will, in alllikelihood, also cause the wire to wear through and becomediscontinuous. If the wire is worn through, then the electricalresistance in the wire will be extremely high (essentially infinite).Thus, by measuring the electrical resistance in the electricallyconductive wire, one can determine whether the wire, and therefore theliner, has worn through.

The electrically conductive wire can also be placed near the outsidesurface of the liner to determine when a significant amount of wear hasoccurred, short of complete wear-through of the liner. In a like manner,a plurality of independent electrically conductive wires could be placedin the liner at varying distances from the abrasive fluid and theresistances of these individually measured to assess wear rate of theliner.

An electrically conductive wire can be placed near the outside surfaceof a liner, for example, by building the wire into the liner. An exampleis provided in FIGS. 14 and 15. FIG. 14 shows an electrically conductivewire 1402 placed in a zigzag pattern near the outside surface 1404 of acylindrically-shaped section of a piping liner 1400. FIG. 15 shows across-sectional view of the liner 1400 that illustrates the wire 1402 isplaced inside the liner 1400, and therefore, near the outside surface1404 of the liner 1400. Preferably, the wire 1402 is placed closer tothe outside surface 1404 of the liner 1400 than the inside surface 1406of the liner 1400.

FIGS. 16 and 17 illustrate another example of how an electricallyconductive wire can be placed near the outside surface of a liner. FIG.16 shows a cylindrically-shaped section of a piping liner 1600 having anelectrically conductive wire 1602 placed near the outside surface 1604of the liner 1600 in a spiral pattern. The wire 1602 is placed in agroove 1606 that has been created in the outside surface 1604 of theliner. The groove 1606 can be created in any suitable manner.Preferably, the depth of the groove 1606 is chosen such that theelectrically conductive wire 1602 is closer to the outside surface 1604of the liner 1600 than the inside surface 1608 of the liner 1600 whenplaced in the groove 1606. The groove 1606 in liner 1600 is spiralshaped, but could be any shape suitable for the application, such as azigzag shape similar to the zigzag pattern shown in FIG. 14. Analternative to the use of electrically conductive wires would be to usetemperature measuring devices, for example, a thermocouple, in order toestimate the amount of wear in the liner. For example, if a lined pipingconstruct is used in an application where high-temperature fluids areinvolved, a temperature measuring device can be advantageously placed onor near the outside surface of the liner. If the liner has heatinsulating properties (such as exhibited by a liner made of a ceramicmaterial) then the device over time will detect a gradually increasingtemperature as the liner wears away and less insulating liner materialseparates the temperature measuring device from the high-temperaturefluid. Monitoring the temperature detected by the device over timeallows the amount of wear on the liner to be estimated. The detectedtemperature at which a liner is sufficiently worn to be replaced willdepend on the temperature of the fluid in contact with the liner, theinsulating properties of the liner, and the thickness of the linermaterial between the temperature measuring device and the fluid.However, a suitable temperature for a given application can bedetermined without undue experimentation by periodically removing aliner and visually inspecting the amount of wear and noting thetemperature detected at the time the liner is removed. Once the wear issufficient to warrant replacement of the liner, the correspondingtemperature can be noted. From that point on, new liners of the sameinsulating material and thickness can be inserted and not removed untilthis temperature is detected or closely approached.

In one embodiment of the present invention, a wire thermocouple isadvantageously utilized as the temperature measuring device. As is knownin the art, a thermocouple can consist of two dissimilar metals joinedso that a potential difference generated between the points of contactis a measure of the temperature difference between the points. In apreferred embodiment of the present invention, the wire thermocouple isa type J or K thermocouple. The wire thermocouple can be placed on ornear the outside surface of the liner in the same manner that theelectrically conductive wire described above is placed and asillustrated in FIGS. 14-17. In another preferred embodiment, the wirethermocouple is also electrically conductive, such that a break in thewire thermocouple can be detected by measuring the electrical resistanceof the electrically conductive wire thermocouple in the same manner thatthe electrical resistance is measured in the electrically conductivewire as described above.

While the present invention has been described in detail with respect tospecific embodiments thereof, it will be appreciated that those skilledin the art, upon attaining an understanding of the foregoing, mayreadily conceive of alterations to, variations of and equivalents tothese embodiments. Accordingly, the scope of the present inventionshould be assessed as that of the appended claims and by equivalentsthereto.

1. A method for detecting wear in a liner containing or bounding a flowof an abrasive fluid, comprising the steps of: placing a temperaturemeasuring device on or near the outside surface of the liner; andmonitoring the temperature measured by the thermocouple over time toestimate wear in the liner.
 2. A method according to claim 1, whereinthe liner is ceramic.
 3. A method according to claim 1, wherein thetemperature measuring device is a wire thermocouple.
 4. A methodaccording to claim 3, wherein the wire thermocouple is placed in azigzag pattern.
 5. A method according to claim 3, wherein the wirethermocouple is placed in a spiral pattern.
 6. A method for detectingwear in a liner containing or bounding a flow of an abrasive fluid,comprising the steps of: creating a groove in the outside surface of theliner; placing a wire thermocouple in the groove; and monitoring thetemperature measured by the wire thermocouple over time to estimate wearin the liner.
 7. A method according to claim 6, wherein the createdgroove comprises a zigzag pattern.
 8. A method according to claim 6,wherein the created groove comprises a spiral pattern.
 9. A methodaccording to claim 6, wherein the liner is ceramic.
 10. A liner,comprising; a substantially cylindrical body of a material which issusceptible of wear over a period of use; and an electrically conductivewire thermocouple placed on or near the outside surface of the body. 11.A liner according to claim 10, wherein the wire thermocouple is placedin a zigzag pattern.
 12. A liner according to claim 10, wherein the wirethermocouple is placed in a spiral pattern.
 13. A liner according toclaim 10, wherein the body is ceramic.
 14. A liner, comprising; asubstantially cylindrical body of a material which is susceptible ofwear over a period of use and which defines a groove in the outsidesurface of the body; and an electrically conductive wire thermocoupleplaced inside the groove.
 15. A liner according to claim 14 wherein thebody is ceramic.
 16. A liner according to claim 14, wherein the groovecomprises a zigzag pattern.
 17. A liner according to claim 14, whereinthe groove comprises a spiral pattern.